1. Field of the Invention
The present invention relates to a slide fastener stringer having a row of continuous fastener elements made of thermoplastic sythetic resin.
2. Prior Art
As is well known in the art, a row of filamentary fastener elements is attached to one longitudinal edge of an elongate sliding clasp fastener stringer by means of sewing threads. Such elongate fastener stringer is cut off into desired lengths each having an element-free gap through which a slider is to be assembled.
The stringer tape is prone to become raveled where it has been severed conventionally by a cutter, and sewing threads which are broken by the cutter near the element-free gap allow fastener elements to loosen and come off. This had led to a drawback in that a slider cannot easily be attached, and the loosened fastener elements can prevent top and bottom end stops from being applied thereto at precise locations.
Various attempts have been made to eliminate the problems. One such effort is a plastic film bonded around the cut edges of the tape and fastener elements. It has also been proposed to impregnate the stringer tape with a synthetic resin solution, or to fuse thermoplastic material in the fastener components at the cut edges. Such prior procedures, however, are disadvantageous in that extra process steps are involved and in that the fastener elements once loosened cannot be properly restored to the fixed position. Furthermore, since the fastener stringer is cut substantially at a right angle to its plane, the thermoplastic material tends to create sharp cut edges which are injurious to the skin or the garments.